Cells exposed to elevated temperatures of chemical stressors respond by synthesizing heat shock proteins (hsp's). The protein expression is thought to represent an adaptive response to protect cells in stress. This project has evaluated the response of rat Sertoli cells in primary culture to the following stresses: cadmium, arsenic, A23187 (calcium ionophore), heat, and an amino acid analogue, in addition to two"industrial" toxicants known to adversely affect Sertoli cells in vivo: MEHP and saligenin cyclic-o-tolyl phosphate. The results indicate that Sertoli cells respond uniquely to each toxicant, and the response to MEHP and SCOTP is unlike the response to the other, "classic" stressors. Further work is needed to evaluate the number of chemicals to which these cells respond, and to develop a way to monitor this response in vivo.